Write a function ngrams(n, tokens) that produces a list of all n-grams of the specified size from the input token list. Each n-gram should consist of a 2-element tuple (context, token), where the context is itself an (n-1)-element tuple comprised of the n-1 words preceding the current token. The sentence should be padded with n-1 "" tokens at the beginning and a single "" token at the end. If n = 1, all contexts should be empty tuples. You may assume that n ≥ 1.

>>> ngrams(1, 'abc')
[('~', 'a'), ('a', 'b'), ('b', 'c')]
>>> ngrams(2, 'abc')
[('~~', 'a'), ('~a', 'b'), ('ab', 'c')]

Explanation:

Assuming input is a string contains space separated words,

like x = "a b c d" we can use the following function

def ngrams(input, n):

input = input.split(' ')

output = []

for i in range(len(input)-n+1):

output.append(input[i:i+n])

return output

ngrams('a b c d', 2) # [['a', 'b'], ['b', 'c'], ['c', 'd']]

If you want those joined back into strings, you might call something like:

[' '.join(x) for x in ngrams('a b c d', 2)] # ['a b', 'b c', 'c d']

Lastly, that doesn't summarize things into totals, so if your input was 'a a a a', you need to count them up into a dict:

for g in (' '.join(x) for x in ngrams(input, 2)):

grams.setdefault(g, 0)

grams[g] += 1

Putting all together

def ngrams(input, n):

input = input.split(' ')

output = {}

for i in range(len(input)-n+1):

g = ' '.join(input[i:i+n])

output.setdefault(g, 0)

output[g] += 1

return output

ngrams('a a a a', 2) # {'a a': 3}

create an interactive presentation of ms powerpoint or any other presentation software in which define the product's characteristics, benefits, why people consider it, etc.

the major difference between the two is the objective and the reward of the game. candy crush has a puzzle theme with the objective of meeting a specific quota of points or objects, you are able to gain access to the next level and compete with peers on the process. on duolingo the objective is rather different, you are given sets of questions for you to answer for you to move to the next level and as for the reward, you are able to learn available language as this is an app developed to teach the user about other languages.